1. Field of the Invention:
This invention relates to recovery of calcium pantothenate from methanol solution.
2. Description of the Prior Art:
Calcium pantothenate is produced by reaction of pantolactone with the calcium salt of beta-alanine in anhydrous methanol solution. U.S. Pat. No. 2,390,499 - Carlson et al, issued Dec. 11, 1945 describes recovery of calcium pantothenate from methanol solution by recrystallization from the solution, by evaporation of the solution or by dilution of the solution with a solvent such as ether, acetone, ethyl acetate or the like which precipitates calcium pantothenate. U.S. Pat. No. 2,496,363 - Wilson et al, issued Feb. 7, 1950, teaches that precipitation of calcium pantothenate from methanol solution requires seeding of methanol solution to accelerate precipitation and that maximum separation of calcium pantothenate from solution requires allowing the solution to stand for extended periods of time. These periods of time vary from 2 to 5 days at room temperature but may be reduced by cooling the solution to 0.degree. C and stirring during crystallization. Example I shows that the calcium pantothenate may be recovered after 2 days standing at room temperature while Example II shows that the calcium pantothenate may be removed after standing 2 days at room temperature and 1 day at 0.degree. C.
Other procedures involving heating the solution to vaporize the methanol leaving behind a residue of solid calcium pantothenate are attended by difficulties in efficient recovery of the methanol.
Calcium pantothenate in methanol solution is reacted with calcium chloride in methanol solution to obtain a calcium chloride complex, the calcium chloride double salt of calcium pantothenate, having the following structural formula: EQU [HOCH.sub.2 C(CH.sub.3).sub.2 CH(OH)CONH(CH.sub.2).sub.2 COO].sub.2 Ca.CaCl.sub.2
Although the double salt is somewhat hygroscopic, it remains relatively free flowing as it absorbs moisture whereas calcium pantothenate readily forms a hard cake with the absorption of moisture. The complex salt has vitamin B activity which makes it suitable for use, without purification, in animal feeds or animal feed supplements. U.S. Pat. No. 2,957,025 - Brooks, issued Oct. 18, 1960, provides additional details on the complex and its use.